AB0488 THE UTILITY OF ERYTHROCYTE SEDIMENTATION RATE, C-REACTIVE PROTEIN, AND PROCALCITONIN IN DETECTING INFECTIONS IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS: A DIAGNOSTIC TEST ACCURACY REVIEW
Authors: S. Bruera, M. Ventura, S. Agarwal, M. A. Lopez-Olivo
Journal: Annals of the Rheumatic Diseases (2022)

Background Patients with systemic lupus erythematosus (SLE) are at an increased risk of hospitalization for flares or infections. In practice, diagnosing SLE flares versus infection can be challenging as both present with similar signs and symptoms. Strategies are needed to help differentiate between infections and SLE flares in hospitalized patients. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and procalcitonin (PCT) are commonly used to aid in the diagnosis of infection in hospitalized patients, however, their utility in SLE is unclear. Objectives To summarize the evidence about accuracy of ESR, CRP, and PCT in diagnosing infection in hospitalized patients with SLE. Methods We searched five databases until April 2021. We included studies published in English investigating levels of ESR, CRP, or PCT on adults hospitalized with a diagnosis of SLE comparing infection versus non-infection. We excluded studies with no clinical data, inadequate data to perform analysis, different conditions, and not relevant study types (such as case reports, other reviews). We also excluded studies with overlapping data (e.g., abstracts that are later published as full-text articles). We used the Quality Assessment of Diagnostic Studies to assess for bias and applicability. We obtained pooled sensitivities and specificities from studies that used similar cut-offs. We also generated mean differences for ESR, CRP, and PCT in infection versus non-infection hospitalized SLE patients. Results We included 26 studies in our analysis. Most studies had an unclear or high risk of bias. Most patients from both infection and non-infection groups were women aged from 27-40 years. The definitions for infection were heterogenous but mainly included positive culture or biochemical testing, suggestive imaging, response to antibiotics, or obvious signs/symptoms (such as purulence). The CRP had a pooled sensitivity of 0.75 (95%CI 0.57-0.94) and specificity of 0.72 (0.59-0.85), PCT had a pooled sensitivity of 0.68 (95% CI 0.0.59-0.77) and specificity of 0.75 (0.59-0.90), and for ESR pooled estimates were not calculated due to insufficient data but sensitivity ranged from 50 to 69.8 and specificity from 38.5 to 55.6. Modifying cut-offs improved sensitivities and specificities (see Table 1). The ESR, CRP, and PCT mean differences were all greater in infection groups versus non-infection (10.1, 95% CI 3.2-17.0; 46.8, 95% CI 36.5-57.0; 0.53, 95% CI 0.26-0.80; respectively). Table 1. Pooled sensitivity and specificities of CRP and PCT Studies(n) Sensitivity(95% CI) Specificity(95% CI) CRP CRP &lt; 10 3 0.68 (0.48-0.89) 0.70 (0.62-0.77) CRP &gt; 10 2 0.91 (0.86-0.97) 0.87 (0.81-0.93) Overall 5 0.75 (0.57-0.94) 0.72 (0.59-0.85) Procalcitonin PCT &gt; 0.2 3 0.66 (0.50-0.81) 0.84 (0.76-0.92) PCT &lt; 0.2 3 0.70 (0.61-0.80) 0.61 (0.53-0.69) Overall 6 0.68 (0.59-0.77) 0.75 (0.59-0.90) Conclusion Our study showed that although ESR, CRP, and PCT mean values are increased in hospitalized infected SLE patients compared to patients with no infection, the included studies used varying cut-offs for sensitivities and specificities and definitions for infection decreasing the uncertainty on the results and making the clinical usefulness of these biomarkers unclear. Our findings at this time do not support the widespread use of these biochemical markers in SLE patients and highlight the need that more research is needed to investigate the use of these markers in this patient population. Disclosure of Interests None declared